div {
  box-sizing: border-box;
  border: 1px solid red;
}
.box1 {
  width: 200px;
  height: 200px;
  background: red;
  display: flex;
}
.box1 .box1-1 {
  width: 50%;
  height: 100%;
}
.box1 .box1-1-1 {
  height: 50%;
  background: blue;
}
.box1 .box1-1-2 {
  height: 50%;
  background: yellow;
}
.box1 .box1-2 {
  flex: 1;
  background: pink;
}
